Improving the Performance of Solution−Processed Quantum Dot Light−Emitting Diodes via a HfOx Interfacial Layer

One of the major obstacles in the way of high−performance quantum dot light−emitting diodes (QLEDs) is the charge imbalance arising from more efficient electron injection into the emission layer than the hole injection. In previous studies, a balanced charge injection was often achieved by lowering...

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Veröffentlicht in:Materials 2022-12, Vol.15 (24), p.8977
Hauptverfasser: Jeong, Jun Hyung, Kim, Min Gye, Ma, Jin Hyun, Park, Min Ho, Ha, Hyoun Ji, Kang, Seong Jae, Maeng, Min-Jae, Kim, Young Duck, Park, Yongsup, Kang, Seong Jun
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Sprache:eng
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Zusammenfassung:One of the major obstacles in the way of high−performance quantum dot light−emitting diodes (QLEDs) is the charge imbalance arising from more efficient electron injection into the emission layer than the hole injection. In previous studies, a balanced charge injection was often achieved by lowering the electron injection efficiency; however, high performance next−generation QLEDs require the hole injection efficiency to be enhanced to the level of electron injection efficiency. Here, we introduce a solution−processed HfOx layer for the enhanced hole injection efficiency. A large amount of oxygen vacancies in the HfOx films creates gap states that lower the hole injection barrier between the anode and the emission layer, resulting in enhanced light−emitting characteristics. The insertion of the HfOx layer increased the luminance of the device to 166,600 cd/m2, and the current efficiency and external quantum efficiency to 16.6 cd/A and 3.68%, respectively, compared with the values of 63,673 cd/m2, 7.37 cd/A, and 1.64% for the device without HfOx layer. The enhanced light−emitting characteristics of the device were elucidated by X−ray photoelectron, ultra−violet photoelectron, and UV−visible spectroscopy. Our results suggest that the insertion of the HfOx layer is a useful method for improving the light−emitting properties of QLEDs.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma15248977